Ergonomics is a field of study on the relationship between people and their working environment. Numerous type of ergonomically compatible products are directed to the comfort and well-being of different portions of a user's body.
Writing instruments have been ergonomically designed to allow a firm gripping and to alleviate the pressure exerted upon the gripping fingers to minimize calluses or fatigue. An ergonomic writing instrument also facilitates its handling by children, senior citizens who may suffer from arthritis or people with handicap.
There are generally two categories of prior art ergonomic writing instruments. The first type of prior art ergonomic writing instruments deviate from the structure of traditional cylindrical writing instruments. For example, U.S. Patent No. 5,564,849 to Joseph M. Greer, Jr. discloses a curved ergonomic pen that facilitates writing on both vertical and horizontal surfaces and U.S. Pat. No. 5,332,324 to Michael A. Hochstetler, which discloses an ergonomic instrument having along its length a spiral groove. A disadvantage of this first type of prior art ergonomic writing instrument results from the deviation from the traditional cylindrical structure because a user must adjust and adapt to gripping the non-uniform structure.
The second type of prior art ergonomic writing instruments include a foam or rubber cushioning placed over the traditional cylindrical structure at the position where the user's thumb and fingers grip. U.S. Pat. No. 5,056,945 to Gerald J. Klodt illustrates one such cushioning grip for writing instruments. A limitation on this second type of prior art ergonomic writing instruments is that the comfort of the user cannot be fully ergonomically realized by the mere addition of a tubular cushioning over the underlying cylindrical structure of the writing instruments.
Therefore, there is a need for an instrument that is ergonomically designed for the comfortable gripping by the user in the natural positioning of the user's thumb and fingers.